1. Field of the Invention
The present invention relates to a technical field of an audio information reproducing system, an audio information reproducing apparatus and an audio information reproducing method. More particularly, the invention relates to the technical field of the audio information reproducing system, the audio information reproducing apparatus and the audio information reproducing method capable of: transmitting both of audio information including voice information and sound information except the voice information and reproducing control information used for controlling a reproducing mode of the audio information; and controlling a reproducing of the audio information using the reproducing control information.
2. Description of the Related Art
In recent years, a DVD whose memory capacity has been enhanced about 7-fold capacity compared to that of a conventional CD (Compact Disk) has come into general use.
Then, as universal standards for digitally recording information in this DVD, a so-called DVD video standard for mainly recording moving picture information such as a movie, and a so-called DVD audio standard for mainly recording high quality audio information have been laid down respectively, these now are being distributed to the concerned such as who prepares moving picture information or who prepares audio information, respectively.
Out of these two standards, in the case of being based on the DVD audio standard, because of its large capacity, for example, control information for the so-called surround reproducing with presence or audio information of three channels or more for it is reproduced at a time, and the surround reproducing can be enjoyed.
In this case, in order to sufficiently enjoy the surround reproducing, it is necessary to use three speakers or more, however, there can be some cases where the user has only a reproducing speaker for right and a reproducing speaker for left.
In order to correspond to such a case, in the DVD audio standard, synthesis coefficients for synthesizing audio information of two channels has been previously prepared as a table by employing audio information of three channels or more and can be recorded with the audio information of the multiple channels in a DVD. Specifically, the audio information of 6 channels is employed in the DVD audio standard described later. The two channels of the synthesized audio information are a channel of reproducing for right side and a channel of reproducing for left side. Further, to reduce the number of channels by the synthesis is generally referred to as down mixing processing.
Now, the synthesis coefficient is a coefficient for synthesizing audio information for right channel and audio information for left channel by multiplying it by a level of audio information of each channel of three channels or more, and in the DVD audio standard, a plurality of kinds of the synthesis coefficients have been prepared as a table and recorded in a DVD.
Moreover, as to the down mixing processing, originally the down mixing processing is performed in the DVD player itself, after making them down-mix-treated for two channels, audio information is outputted to the external. However, in consideration of a simplified DVD player, reproducing in a higher quality may be performed by the procedure such that the above described synthesis coefficient is outputted with audio information of multiple channels of three channels or more into an amplifier without performing the down mixing processing itself in the DVD player, the down mixing processing is carried out in the amplifier and down-mix-treated information is outputted to the speaker, etc. The amplifier is one in which audio information outputted from the DVD player is submitted to amplification processing and the audio information is outputted into the speaker, etc.
On the other hand, in recent years, as a new standard for transmitting information in real time via a serial bus between a plurality of information processing apparatuses, for example, personal computer and digital video camera or MD (Mini Disk) player and the like, the so-called IEEE1394 standard (the officially approved name is “IEEE Std. 1394-1995 IEEE Standard for a High Performance Serial Bus”) has been published. A digital video camera, a personal computer and the like equipped with a serial port being in conformity with the standard are being manufactured.
In this IEEE 1394 standard, it is standardized so that by connecting via a serial bus between a plurality of information processing apparatuses (hereinafter, referred to as simply node) such as an optical disk player, an amplifier or the like, transmission of information of the portion of multiple channels is carried out in a time divisional manner between these respective nodes. In the standard, it is standardized that transmission of information can be carried out by employing different 63 channels at the maximum within a system connected via one serial bus.
Now, in the IEEE 1394 standard, in the case where a new other node is connected with the node group mutually connected already via a serial bus one another (i.e., during bus connection), or in the case where one of the nodes is removed from the above described node group (i.e., during bus disconnection), it is standardized that the initialization of a serial bus which is referred to as the so-called bus reset is carried out. Then, a new connection mode (hereinafter, the connection mode is referred to as topology) of a serial bus is constructed in accordance with the predetermined procedure that previously has been set after the bus reset.
Then, in the case where information is actually transmitted after constitution of topology, transmission node and IRM (Isochronous Resource Manager) node are used. The transmission node is a node for initiating transmission of the information. The IRM node is a node for controlling the communication state of all of the nodes within the constituted topology, and displaying a channel used at present and transmission occupying time occupied by each nodes at present so that other node can be distinguish them. Specifically, the communication state which is controlled by the IRM node is a channel used of each node and transmission occupying time described later.
At first, the transmission node inquires of IRM node the communication state of the other nodes at present. Then, if the channel and transmission occupying time which the transmission node itself would like to use can be used, the transmission node acquires the right to transmit information. More concretely, the transmission node secures a channel for use by the transmission node and the transmission occupying time described later. Then, the transmission node initiates the transmission of the information. At the moment, immediately before the transmission of the information, the transmission node transmits the effect that display of the communication state in the above described IRM node is rewritten to the IRM node. Since the occupied channel and transmission occupying time on a serial bus are changed by the transmission node for initiating the transmission of information, it is required that the display contents are rewritten to a new communication state after this change. The IRM node which has received the effect carries out the processes for updating the display contents, respectively. Hereinafter, the display contents after the updating can be made reference from the other nodes, respectively.
Next, the above described transmission occupying time will be briefly described below.
In the IEEE 1394 standard, information from respective nodes are grouped in every unit which is referred to as an isochronous cycle and sent out. The term “cycle” is referred to a cycle formed by dividing in a time diving manner on a serial bus. The isochronous cycle includes: an isochronous transmission region including information transmitted in synchronization with the information within the other isochronous cycle and asynchronous transmission region including information transmitted in asynchronization irrelevant to the other information. Concretely, the information within the isochronous transmission region includes image information, audio information or the like. The information within the asynchronous transmission region includes control information for controlling an output and the like of the above described image information or audio information, and the like. Then, the information within the isochronous transmission region is time-shared in every different channel, and different information in every channel is transmitted, respectively.
In the isochronous transmission region, it is standardized that the time length of isochrouns transmission region within one of the isochronous cycles is 100 μ sec at the maximum. Therefore, it is required that the total time which the information assigned for respective channels within one isochronous transmission region occupies for its transmission is also made to be 100 μ sec. The transmission time which the one channel occupies within an isochronous cycle is the above described transmission occupying time.
It should be noted that the transmission occupying time may be also referred to as a working bandwidth of a serial bus depending on the situation, and may be also referred to as a working capacity of a serial bus.
On the other hand, within one isochronous cycle, when the length of the isochronous transmission region is less than 100 μ sec (including the case of 0), a time within isochronous cycle except the isocrhronous transmission region is exclusively used as an asynchronous transmission region.
According to the IEEE 1394 standard having an outline described above, since the transmission of, for example, copy control information or the like except transmission information can be possible as well as a large capacity of information can be rapidly transmitted not depending on the attribute of image information, audio information or the like in the transmission information to be transmitted, it is possible to transmit information while taking all possible measures to ensure the protection of copyright with respect to the transmission information.
However, in consideration of the case where the above described DVD player and amplifier are connected via the serial bus of the above described IEEE 1394 standard, audio information of a plurality of three channels or more as described above and a synthesis coefficient for down mixing processing are transmitted from the DVD player to the amplifier and the down mixing processing is carried out, there is a problem that since the synthesis coefficient has a large capacity of information, all of the synthesis coefficient cannot be transmitted at a time within the one isochronous cycle described above nor can be the down mixing processing carried out.
Specifically, although the above described synthesis coefficient has been previously set per one audio information of a plurality of channels to be treated by the down mixing processing and recorded in a DVD, since its information is information of a large amount as described above, it cannot be transmitted at a time within one isochronous cycle. Therefore, one synthesis coefficient has only to be resolved and they have to be individually transmitted with time differences by employing a plurality of isochronous cycles, however, in this case, there may be some instances where audio information in the amplifier after transmission and synthesis coefficient to be employed for its down mixing processing cannot be corresponded, and in this case, the down mixing processing cannot be carried out based on the predetermined association.